Date.prototype.yyyymmdd = function() {
    var yyyy = this.getFullYear().toString();
    var mm = (this.getMonth() + 1).toString(); // getMonth() is zero-based
    var dd = this.getDate().toString();
    return yyyy + "-" + (mm[1] ? mm : "0" + mm[0]) + "-" + (dd[1] ? dd : "0" + dd[0]); // padding
};

var is_mobile = /mobile|android/i.test (navigator.userAgent);